1. Field of the Invention
The present invention pertains to binoculars capable of performing zooming.
2. Description of the Prior Art
In the conventional construction of zoom binoculars, the zoom operating member is located around the right eyepiece optical system and zooming is performed by rotating the member around the optical axis of the right eyepiece optical system. FIG. 8 shows the construction of conventional zoom binoculars. It shows one example of Porro prism binoculars using a structure in which the eye distance, i.e. distance of two optical axes, is adjusted using one shaft as the rotating axis. Portion (a) of FIG. 8 is a longitudinal sectional plan view and (b) is a transverse sectional front elevation.
Numeral 6 indicates eyepiece zoom optical systems. Each eyepiece zoom optical system is mounted inside a movable lens holder 5 having an essentially cylindrical configuration such that the eyepiece optical axis 9 runs through its center. The movable lens holder 5 is movably engaged with an essentially cylindrical cam 8 located around the lens holder 5. A cam pin 4 protrudes outward from the outer circumference of the movable lens holder 5. It extends through a cam groove of the cam 8 and reaches a guide member 7 located outside the cam 8. The guide member 7 has a guide groove 10. By means of the cam pin 4 engaging with the guide groove 10, the movable lens holder 5 is guided straight forward or backward along the eyepiece optical axis 9.
An essentially cylindrical right zoom drive member 18 is located around the outer circumference of the right guide member 7. As shown in (b) of FIG. 8, a zoom operating member 13 protrudes outward from the outer circumference of the right zoom drive member 18. By manually operating this member 13 in the directions indicated by the two-headed arrow, the right zoom drive member 18 rotates around the right eyepiece optical axis 9. Further, a claw 18a protrudes from one end of the right zoom drive member 18. By means of the claw 18a engaging with the right cam member 8, the rotational movement of the right zoom drive member 18 is transmitted to the right cam member 8.
An essentially cylindrical left zoom drive member 21 is located around the outer circumference of the left guide member 7. This left zoom drive member 21 is linked to the right zoom drive member 18. When the right zoom drive member 18 rotates, the left zoom drive member 21 rotates around the left eyepiece optical axis 9. The mechanism by which the rotational movement of the left zoom drive member 21 is transmitted to the left cam 8 is the same as for the right unit.
Based on this construction, the left and right cams 8 rotate their respective eyepiece optical axes 9, and the rotational movement of the left and right cams 8 is transmitted to the left and right cam pins 4 through the cam grooves, respectively, whereupon the left and right movable lens holders 5 move along the eyepiece optical axes 9 and zooming is achieved.
The rotational movement of the right zoom drive member 18 is transmitted to the left zoom drive member 21 by means of a connecting member 11, which comprises an elastic member having a long and narrow plate spring configuration. In other words, engaging portions 11a and 11b are located on either end of the connecting member 11, and these engage and link with one portion of the outer circumference of the right zoom drive member 18 and one portion of the outer circumference of the left zoom drive member 21, respectively. The connecting member 11 is constructed such that it passes through the eye distance adjusting axis 22. The reason for this is explained below.
In binoculars, the left and right eyepiece optical systems are connected to each other such that they can rotate around the eye distance adjusting axis 22 for the purpose of so-called eye distance adjustment, by which the distance between the left and right eyepiece optical axes 9 is adjusted to match the distance between the eyes of the user. If the connecting member 11 did not pass through the eye distance adjusting axis 22, when the left and right eyepiece optical systems rotated around the axis 22, the positional relationship between the right zoom drive member 18 and the left zoom drive member 21 would change.
FIG. 9 shows another conventional technology.
The binoculars shown in FIG. 9 comprise three units, i.e., a housing 15 and left and right optical units 16 and 17 incorporated in the housing. They comprise Porro prism binoculars using a structure in which the eye distance is adjusted around two axes.
A zoom operating member 14 is located in the center of the binoculars, and a zoom mechanism 35 is located in the housing 15. By operating the zoom operating member 14 in the directions indicated by the two-headed arrow, the zoom mechanism 35 moves left or right, by which the connecting member 11 is driven left or right and the right zoom drive member 18 and left zoom drive member 21 rotate together. The locational relationships among the cam pins 4, movable lens holders 5, guide members 7, cams 8 and eyepiece optical axes 9 are the same as in the binoculars shown in FIG. 8.
In the first construction, the zoom operating member 13 rotates essentially as one unit with the cam 8, and therefore, the construction must be such that the zoom operating member 13 rotates around the eyepiece optical axis 9. This creates the problems that there is little freedom in arranging the components and the zooming operation is difficult.
If it were attempted to use the second construction in binoculars using the method in which the eye distance is adjusted around one axis, it would become impossible to have the connecting member 11 pass through the eye distance adjusting axis. Therefore, the construction shown in FIG. 9, in which there are two (left and right) rotational axes for eye distance adjustment (not shown in the drawing) must be used, which creates the problem that the binoculars comprise three units and the entire mechanism becomes larger in size to the extent of the housing 15.
In view of these problems, the object of the present invention is to provide compact zoom binoculars in which the zoom operating member is in a location that allows easy operation.
In order to attain this object, one aspect of the present invention has a zoom operating member and left and right zoom drive members connected to each other, wherein one of the left and right zoom drive members is connected to and moves together with the zoom operating member in a non-integrated fashion.
In addition, the connecting member that connects the left and right zoom drive members is located such that it passes through the eye distance adjusting axis. The zoom operating member is located above the eye distance adjusting axis. The zoom operating member is connected to the zoom drive member on the side at which a focus drive member is located. There is one eye distance adjusting axis.
These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings, which illustrate specific embodiments of the invention.